We music geeks are, by and large, completists. Record companies know this, which is why, even in an era when physical media is becoming a thing of the past, they keep releasing “deluxe,” “expanded” or “complete” editions of classic rock albums.
The formula is generally this. Remix the album in question, add a disc or two of alternate versions of songs and maybe a few tunes that didn’t make the cut when the album was initially released, and find some live recordings (sometimes an entire concert) from the era. Throw in reproductions of ephemera (backstage passes, decals, maybe a poster) and perhaps a modest coffee table book, and you’ve got something that can be sold for a premium price. And that’s how you generate some cash flow from material that has already been bought and paid for.